Four-Bar Linkage for Suspending a Header for an Agricultural Implement

ABSTRACT

A suspension system for agricultural implements having at least one floating head using a four-bar linkage and permitting the floating head to accommodate variations in ground surface elevation in a lateral or transverse direction. By permitting the floating head to float, a more consistent cutting height is realized when ground surface elevation varies in a transverse direction. A main frame is provided to which the ground engaging wheels are attached. A sub-frame is connected to the main frame via the four-bar linkage. The sub-frame is pivotally attached to the arms of the four-bar linkage by spherical bearings.

CROSS REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an agricultural implement,including a floating work tool. More particularly, the present inventionrelates to an improved suspension system for agricultural implementshaving one or more floating work tools.

2. Background Art

Ground on which forage crops or other foliage needing mowing is grown israrely smooth. Such ground essentially always varies in level both in adirection of travel of the mowing machine or harvester, and in atransverse or lateral direction.

Mowing machines having a variable height cutter have been available fordecades. Mounted sickle mowers used in the mid-twentieth century couldbe raised and lowered using the tractor lift system. Towed mowers, bynecessity, were made so the header could be raised and lowered, at leastbetween an operating position and a transport position.

In U.S. Pat. No. 6,250,055, a mower header suspension system isdisclosed. The suspension system comprises a pair of lower linkage armsand a single upper suspension arm. Provision for changes in groundelevation in the direction of travel is disclosed.

Disclosed in U.S. Pat. No. 6,055,800 is a mower header suspension systemproviding a variable header angle compared to the longitudinaldirection. The disclosed mechanism comprises two lower linkage arms anda single upper linkage arms.

The above described header suspension systems provide for changing theheight of cut relative to the ground surface supporting the groundengaging wheels of the tractor or towed mower, but do not provide for aconsistent cut height on ground that varies in level both in thedirection of travel and in the lateral direction.

There is, therefore, a need for a method and apparatus for providingflexibility in header position to permit the header to raise and loweras ground elevation changes, and to rotate to adjust to lateralvariations in ground surface levels.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to provide a suspension systemthat enables a header or work tool of a towed implement to be raised andlowered, and also permit the header or work tool to follow the variableground contour, resulting in a consistent cut height despite thevariability of the ground elevation.

For the purposes of this document, including the claims, a towedimplement is an implement with ground engaging means, for examplewheels, independent of the source of motive power, for example a farmtractor; additionally, the towed implement has a frame or othercomponent that may be raised and lowered relative to the ground engagingmeans independent of a lift, such as a standard three-point or two-pointlift system of the source of motive power. Therefore, a towed vehicle ispulled by the source of motive power and my use the source of motivepower's hydraulic system for raising and lowering, but does not make useof lift arms usually attached to a farm tractor.

The mower comprises two integrated frames connected by two sets oflinkages to create a four-bar linkage. The two sets of linkages aremaintained parallel to one another, so that the two frames aremaintained at a known orientation to one another as the header is raisedand lowered.

The upper linkage set comprises two “bars,” oriented at angles withrespect to a longitudinal axis of the mower such that they connect tothe sub-frame at points nearer the longitudinal axis than those pointsat which they connect to the main frame. In contrast, the lower linksare angled such that they connect to the sub-frame at points fartherfrom the longitudinal axis than those points at which the lower linksconnect to the main frame.

Spherical bearings are used to connect each independent bar of the lowerlinkage set to the main frame and to the sub-frame. As well, sphericalbearings are also used to connect the upper linkage bars to thesub-frame. The upper linkage bars are pivotally attached to the mainframe by cylindrical bearings.

In a first embodiment, the upper linkage bars are permanently connectedto one another where the upper linkage bars converge at the sub-frame,and are subsequently connected to the sub-frame using a single sphericalbearing. In an alternative embodiment, the two bars are not directlyconnected to one another, but are pivotally connected to the sub-frameby independent spherical bearings in the same manner as the lowerlinkage bars.

The linkage arrangement herein described allows the sub-frame theability to rotate about an axis of rotation parallel to the longitudinalaxis of the mower. This ability is called “float” and refers to thecapability of the mower to adjust itself automatically to a ground slopeperpendicular to the direction of travel.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a side elevation of a mower machine in a transportconfiguration;

FIG. 1 b is a side elevation of the mower machine in an operatingconfiguration;

FIG. 2 is a rear elevation view of the mower showing a four-bar linkagesystem arrangement;

FIG. 3 is a left side elevation view of the rear of the mower showingthe main frame mounted on wheels and indicating the parallelism of thetwo linkage levels;

FIG. 4 is a left side elevation view of the rear of the mower showingthe pivot point in the sub-frame about which the cutter bar pitch iscontrolled;

FIG. 5 a is a top plan view of the sub-frame in a transportconfiguration showing both arms rotated inward toward the longitudinalaxis;

FIG. 5 b is a top plan view of the sub-frame in an operatingconfiguration showing both arms 8 rotated outward from the longitudinalaxis;

FIG. 6 a is an isometric view of the mower in transport configuration;

FIG. 6 b is an isometric view of the mower in operational configuration;

FIG. 7 is a rear elevation view of the mower in a first embodiment ofthe present invention;

FIG. 8 is a rear elevation view of the mower in a second embodimenthaving individual links at a top of the four-bar linkage system;

FIG. 9 is a rear elevation view of the mower presenting a thirdembodiment of the four-bar linkage system in which the orientations ofthe upper and lower linkage sets are opposite of those in the firstembodiment;

FIG. 10 is a rear elevation view of the mower presenting a fourthembodiment of the four-bar linkage system in which the orientations ofthe upper and lower linkage sets are opposite of those in the secondembodiment;

FIG. 11 a is a top plan view of the mower with its header in anoperating position illustrating a leveling mechanism;

FIG. 11 b is a side elevation view of the mower with its header in anoperating position illustrating the leveling mechanism;

FIG. 12 a is a top plan view of the mower with its header in a transportposition illustrating the leveling mechanism; and

FIG. 12 b is a side elevation view of the mower with its header in atransport position illustrating the leveling mechanism.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals indicateidentical or corresponding parts throughout the several views, thepresent invention comprises a suspension system for an agriculturalmower 1, shown in its entirety in FIGS. 1 a, 1 b, 6 a, and 6 b. Themower 1 comprises two integrated frames 10, 15. A tongue 2 extendingover the machine is pivotally connected to a top of a main frame 15,positioned at the extreme rear of the agricultural mower 1. The mainframe 15 has left and right legs mounted atop axles between two groundengaging wheels for supporting the agricultural mower 1 on the ground65. The axis of rotation of these wheels is substantially perpendicularto a direction of travel. A sub-frame 10 is pivotally connected to themain frame 15, forward of the main frame 15 by means of a four-barlinkage system. The sub-frame 10 is a two part frame, suspending thework tool or cutter bar 9.

The tongue 2 is preferably connected to an agricultural tractor (notshown). The mower 1 is normally drawn in a direction toward the tongue2, which direction is hereby defined as the forward direction. Based onthis, the rearward direction is hereby defined for the purposes of thisdocument, including the claims as opposite the forward direction.

A front of the mower 1 is likewise hereby defined as the general portionof the mower 1 in the lead as the mower 1 is drawn in the forwarddirection. A rear of the mower 1 is hereby defined as the generalportion of the mower 1 seen when viewed from a side of the mower 1opposite the tongue and facing in the forward direction.

A longitudinal direction is hereby defined as a direction parallel tothe forward direction. A transverse direction is hereby defined as adirection perpendicular to the longitudinal direction, and parallel toan appropriate average of a slope of the ground surface in the vicinityof a header 6.

The above definitions are defined for the purposes of this document,including the claims. The present invention comprises a four-bar linkagesystem including an upper set of linkages 12 and a lower set of linkages11, each comprising two bars as illustrated in FIGS. 2-4 and 7-10. Theupper linkage set 12 and the lower linkage set 11 are substantiallyparallel to one another when considering a side elevation view such asthose featured in Figs. la and lb. As shown in the plan views of FIGS. 5a and 5 b, and the rear elevation view, FIG. 7, the bars belonging tothe upper linkage set 12 are oriented in such a way as to be angled withrespect to a longitudinal axis 52 of the mower 1. More precisely, theupper links 12 are angled such that they connect to the sub-frame 10 atpoints nearer the longitudinal axis 52 than those points at which theupper links 12 connect to the main frame 15. The lower links 11 areangled such that they connect to the sub-frame 10 at points farther fromthe longitudinal axis 52 than those points at which the lower links 11connect to the main frame 15.

Each independent bar of the lower linkage set 11 is pivotally connectedto the main frame 15 by a spherical bearing, also known as a ball joint,at a first point and is pivotally connected to the sub-frame 10 by aspherical bearing, also known as a ball joint, at a second point. Asillustrated in FIGS. 7-10, each bar of the upper linkage 12 is pivotallyconnected to the main frame 15 by a cylindrical bearing at a first pointand pivotally connected to the sub-frame 10 by a spherical bearing, alsoknown as a ball joint, at a second point. In a first embodiment, theupper linkage bars 12 are rigidly affixed to one another where the upperlinkage bars 12 converge at the sub-frame 10, and are connected to thesub-frame 10 with a single spherical bearing, as shown in FIG. 7. In asecond embodiment, illustrated in FIG. 8, the two bars upper linkagebars 12 are not directly connected to one another, but are pivotallyconnected to the sub-frame 10 by independent spherical bearings in thesame manner as the lower linkage bars 11. In this second embodiment, theends of the upper linkage bars 12 nearest the sub-frame 10 are disposedcloser together than their ends nearest the main frame 15. In either ofthe first and second embodiment, the lower linkage bars 11 diverge fromone another as they extend from the main frame 15 to the sub-frame 10.

In a third embodiment, the lower link arms 11 are rigidly affixed to oneanother where the lower linkage bars 11 converge at the sub-frame 10,and are connected to the sub-frame 10 with a single spherical bearing,as shown in FIG. 9. In a fourth embodiment, illustrated in FIG. 10, thetwo lower linkage bars 11 are not directly connected to one another, butare pivotally connected to the sub-frame 10 by independent sphericalbearings in the same manner as the upper linkage bars 12. In this fourthembodiment, the ends of the lower linkage bars 11 nearest the sub-frame10 are disposed closer together than their ends nearest the main frame15. In either of the first and second embodiment, the upper linkage bars12 diverge from one another as they extend from the main frame 15 to thesub-frame 10.

The linkage arrangement described above allows the sub-frame 10 torotate about an axis of rotation parallel to the longitudinal axis 52.This ability is hereby defined as float for the purposed of thisdocument, including the claims, and implies the capability of the mower1 to adjust itself automatically to a ground slope perpendicular to thedirection of travel. As illustrated especially in FIGS. 5 a, 5 b, 6 a,and 6 b, the two independent headers 6 are supported independently bytheir respective arms 8 on cylindrical bearings, allowing each cutterbar 9 to float independently. Therefore, the undersides of the cutterbars 9 engage the ground surface 65 with greater consistency due totheir floating ability. The two arms 8, pivotally mounted to the top ofthe forward portion of the sub-frame 10, have a vertical axis ofrotation. The cutter bars 9 mounted from these arms 8 are then allowedto pivot toward or away from the longitudinal axis 52. As shown in FIGS.1 a, 5 a, and 6 a, in a transport position, the arms 8 are rotatedforward, thereby decreasing a width of the mower 1. In an operatingmode, illustrated in FIGS. 1 b, 5 b and 6 b, the arms 8 are rotatedtoward the rear of the mower 1 such that the two separate cutter bars 9form a single row perpendicular to the direction of travel. Thesub-frame lift cylinder 14 is used to raise the sub-frame 10 off theground 65 for transport. The sub-frame 10 is provided with a lockingarrangement for the transport position to eliminate the risk of thesub-frame 10 dropping to the ground 65 during transport.

The present invention realizes significant benefit in that thesuspension system mounts the sub-frame 10 in such a way as to give thesub-frame 10 multi-directional motion freedoms such that the undersideof the cutter bar 9 is allowed to more consistently engage the groundsurface 65 as the ground surface 65 varies. This results in the benefitof a more consistent cut height.

Another significant benefit is realized by the converging and divergingarrangements of the lower linkage bars 11 and the upper linkage bars 12,in combination with the illustrated orientation sub-frame lift cylinder14. Due to the lower linkage bars 11 being in tension whenever thesub-frame lift cylinder 14 is retracted, the header 6 is self-levelingwhen in the transport position, while the header 6 is permitted to beparallel to the ground when in the operating position. Further, due tothe tension in the lower linkage bars 11, the header will tend to centeritself relative to the main frame 15 on retraction of the sub-frame liftcylinder 14.

An additional leveling feature is illustrated in FIGS. 11 a-12 b. As theheader is raised from the operating position (FIGS. 11 a and 11 b), tothe transport position (FIGS. 12 a and 12 b), and the upper linkage bars12 reach an extreme raised position, they make contact with a levelingbracket 75, causing the sub-frame 10, 62 to become parallel to theground contour in the transverse direction. A benefit is that if oneside of the header becomes heavy due to accumulation of crop material,etc., it will still become level. This also keeps the sub-frame 10 fromswaying while the agricultural mower 1 is in its transport position.

The embodiments of the novel suspension system herein described may beutilized for any implement making use of a floating work tool. Theinvention is not intended to be limited to agricultural mowers.

The above embodiments are the preferred embodiments, but this inventionis not limited thereto. It is, therefore, apparent that manymodifications and variations of the present invention are possible inlight of the above teachings. It is, therefore, to be understood thatwithin the scope of the appended claims, the invention may be practicedotherwise than as specifically described.

1. (canceled)
 2. A method of suspending a header from a towed implementto permit the header to float, the towed implement comprising a mainframe, a sub-frame, and a four-bar linkage system comprising an upperlink and a lower link, the method comprising: (a) operatively, pivotallyattaching a first end of the lower link to the main frame of the towedimplement using a first spherical bearing; (b) operatively, pivotallyattaching a second end of the lower link to the sub-frame using a secondspherical bearing; (c) operatively, pivotally attaching a first end ofthe upper link to the main frame using a first cylindrical bearing; (d)operatively, pivotally attaching a second end of the upper link to thesub-frame using a third spherical bearing; and (e) operatively attachingthe header of the towed implement to the sub-frame; (f) operatively,pivotally affixing an actuator to the sub-frame above the upper link;(g) applying a force to the sub frame with the actuator in a directiontoward the main frame; (h) placing the lower link in tension due to theforce; (i) raising the sub-frame due to the force; (j) permitting thesub-frame to self-level due to the tension in the lower link; and (k)wherein the lower link comprises a first lower link and the upper linkcomprises a first upper link, the towed implement additionallycomprising a second lower link and a second upper link, the methodadditionally comprising: (a) operatively, pivotally attaching a firstend of the second lower link to the main frame of the towed implementusing a fourth spherical bearing; (b) operatively, pivotally attaching asecond end of the second lower link to the sub-frame using a fifthspherical bearing; (c) operatively, pivotally attaching a first end ofthe second upper link to the main frame using a second cylindricalbearing; and (d) operatively, pivotally attaching a second end of thesecond upper link to the sub-frame using a sixth spherical bearing. 3.The method of claim 2 additionally comprising operatively, rigidlyattaching the second end of the first upper link to the second end ofthe second upper link.
 4. The method of claim 2 additionally comprisingdisposing the first end of the first lower link nearer the first end ofthe second lower link than the second end of the first lower link to thesecond end of the second lower link.
 5. The method of claim 2additionally comprising disposing the second end of the first upper linknearer the second end of the second upper link than the first end of thefirst upper link to the first end of the second upper link.
 6. Themethod of claim 2 additionally comprising disposing the second end ofthe first lower link nearer the second end of the second lower link thanthe first end of the first lower link to the first end of the secondlower link.
 7. The method of claim 2 additionally comprising disposingthe first end of the first upper link nearer the first end of the secondupper link than the second end of the first upper link to the second endof the second upper link.
 8. The method of claim 2 additionallycomprising: (a) operatively, pivotally affixing an actuator to thesub-frame above the first and second upper links; (b) applying a forceto the sub frame with the actuator in a direction toward the main frame;(c) placing the upper links in compression due to the force; (d) placingthe lower links in tension due to the force; (e) raising the sub-framedue to the force; and (f) permitting the sub-frame to self-level due tothe tension in the lower links.
 9. A towed implement comprising: (a) amain frame having a front, a left side and a right side; (b) a firstground engaging wheel disposed on the left side of the towed implementfor supporting the towed implement, the towed implement having alongitudinal axis substantially perpendicular to an axis of rotation ofthe first ground engaging wheel; (c) a second ground engaging wheeldisposed on the right side of the towed implement for supporting thetowed implement; (d) a sub-frame for supporting a work tool; (e) a leftlower link having a first end operatively, pivotally connected to themain frame by a spherical bearing; and a second end operatively,pivotally connected to the sub-frame by a spherical bearing; (f) a rightlower link having a first end operatively, pivotally connected to themain frame by a spherical bearing, and a second end operatively,pivotally connected to the sub-frame by a spherical bearing; and (g) anupper link having a first end operatively, pivotally connected to themain frame by a cylindrical bearing, and a second end operativelypivotally connected to the sub-frame by a spherical bearing.
 10. Thetowed implement of claim 9 wherein the upper link comprises a left upperlink, the towed implement additionally comprising a right upper linkhaving a first end operatively, pivotally connected to the main frame bya cylindrical bearing, and a second end operatively, pivotally connectedto the sub-frame by a spherical bearing.
 11. The towed implement ofclaim 10 wherein the second end of the left upper link is operatively,rigidly affixed to the second end of the right upper link.
 12. The towedimplement of claim 9 wherein the first end of the left lower link andthe first end of the right lower link are disposed nearer to one anotherthan the second end of the left lower link and the second end of theright lower link.
 13. The towed implement of claim 9 wherein the firstend of the left lower link and the first end of the right lower link aredisposed farther apart relative to one another than the second end ofthe left lower link and the second end of the right lower link.
 14. Thetowed implement in claim 10 wherein the first end of the left upper linkand the first end of the right upper link are disposed nearer to oneanother than the second end of the left upper link and the second end ofthe right upper link.
 15. The towed implement in claim 10 wherein thefirst end of the left upper link and the first end of the right upperlink are disposed farther apart relative to one another than the secondend of the left upper link and the second end of the right upper link.16. The towed implement of claim 9 additionally comprising a tongue,operatively, pivotally connected to the main frame.
 17. The towedimplement of claim 9 wherein the sub-frame is disposed in front of themain frame.
 18. The machine of claim 9 wherein the left lower link andupper link are substantially parallel when viewed from a transversedirection.
 19. A towed implement comprising: (a) a main frame having afront, a left side and a right side; (b) a first ground engaging wheel,disposed on the left side of the main frame for operatively supportingthe towed implement on the ground, the main frame additionallycomprising a longitudinal axis substantially perpendicular to an axis ofrotation of the first ground engaging wheel; (c) a second groundengaging wheel, disposed on the right side of the main frame foroperatively supporting the towed implement on the ground; and (d) atwo-piece sub-frame for supporting a work tool wherein a first portionof the sub-frame is operatively, pivotally connected to the main frame,and a second portion of the sub-frame is operatively, pivotallyconnected to the work tool.
 20. The towed implement of claim 19additionally comprising: (a) a left lower link having a first endoperatively, pivotally connected to the main frame by a sphericalbearing; and a second end operatively, pivotally connected to thesub-frame by a spherical bearing; (f) a right lower link having a firstend operatively, pivotally connected to the main frame by a sphericalbearing, and a second end operatively, pivotally connected to thesub-frame by a spherical bearing; and (g) an upper link having a firstend operatively, pivotally connected to the main frame by a cylindricalbearing, and a second end operatively pivotally connected to thesub-frame by a spherical bearing.
 21. The towed implement of claim 19wherein the upper link comprises a left upper link, the towed implementadditionally comprising a right upper link having a first endoperatively, pivotally connected to the main frame by a cylindricalbearing, and a second end operatively, pivotally connected to thesub-frame by a spherical bearing.
 22. The towed implement of claim 21wherein the second end of the left upper link is operatively, rigidlyaffixed to the second end of the right upper link.
 23. (canceled)
 24. Amethod of suspending a header from a towed implement to permit theheader to float, the towed implement comprising a main frame, asub-frame, and a four-bar linkage system comprising an upper link and alower link, the method comprising; (a) operatively, pivotally affixingan actuator to the sub-frame of the towed implement above the upperlink; (b) applying a force to the sub frame with the actuator in adirection toward the main frame; (c) placing the upper link incompression due to the force; (d) placing the lower link in tension dueto the force; (e) raising the sub-frame due to the force; (f) permittingthe sub-frame to self-level due to the tension in the lower link; and(g) wherein the upper link comprises a first upper link having a firstend and a second end, and the lower link comprises a first lower linkhaving a first end and a second end, and wherein the towed implementadditionally comprises a second upper link having a first end and asecond end and a second lower link having a first end and a second end,the method further comprising: (a) disposing the first end of the firstlower link nearer the first end of the second lower link than the secondend of the first lower link to the second end of the second lower link;(b) disposing the first end of the first upper link nearer the first endof the second upper link than the second end of the first upper link tothe second end of the second upper link; (c) placing the first andsecond upper links in compression due to the force; (d) placing thefirst and second lower links in tension due to the force; (e) permittingthe sub-frame to center on the main frame due to the tension in thefirst and second lower links. 25-31. (canceled)
 32. A method ofstabilizing a header on a towed implement, the towed implementcomprising a main frame, a sub-frame, and a four-bar linkage system,said four-bar linkage system comprising an upper link, a first lowerlink, and a second lower link, the method comprising: (a) configuringthe sub-frame to have a sub-frame width defined by a first sub-frameside and a second sub-frame side; (b) configuring the header to have anoverall operating width defined by a first header end and a secondheader end, said overall operating width being measured when the headeris disposed in an operating position, wherein the sub-frame width issubstantially less than the overall operating width; (c) connecting anend of the first lower link to the sub-frame at the first sub-frameside; and (d) connecting an end of the second lower link to thesub-frame at the second sub-frame side. 33-35. (canceled)